title: In vitro study of a novel oxysterol for osteogenic differentiation on rabbit bone marrow stromal cells.
abstract: BACKGROUND
  Bone morphogenetic proteins (BMPs) are powerful osteoinductive growth factors but are associated with exorbitant costs and undesirable side effects. Oxysterols are biocompatible cholesterol oxidation products with osteoinductive properties that may represent an alternative to BMP. In this study, the authors examine the osteogenic potential and mechanisms of actions of oxysterol 49, a novel oxysterol analogue, in primary rabbit bone marrow stromal cells.
  
  
  METHODS
  Bone marrow stromal cells were isolated from the iliac crests of New Zealand White rabbits and then treated with various concentrations of oxysterol 49 or BMP-2, either alone or in combination. Alkaline phosphatase activity and expression of osteocalcin and osteopontin were evaluated. The effect of treatment of cells with cyclopamine, a known hedgehog signaling pathway inhibitor, was also assessed.
  
  
  RESULTS
  Alkaline phosphatase activity was increased in cells treated with 1 µM oxysterol 49 relative to cells treated with BMP-2. Expression of osteocalcin and osteopontin in cells treated with oxysterol 49 and BMP-2 was equivalent. Alkaline phosphatase activity was decreased with the addition of cyclopamine. Combined treatment with oxysterol 49 and BMP-2 resulted in additive increases in alkaline phosphatase activity and osteocalcin and osteopontin expression.
  
  
  CONCLUSIONS
  Oxysterol 49 has osteoinductive properties that are similar to those of BMP-2 in rabbit bone marrow stromal cells. The mechanism of this activity is at least in part related to the hedgehog signaling pathway. The two growth factors demonstrate additive effects when used in combination. Further study is required to examine the potential role of oxysterol 49 as a complement or alternative to BMP-2 in bone tissue engineering.
authors.affiliation: Los Angeles, Calif. From the Division of Plastic and Reconstructive Surgery, Department of Surgery, David Geffen School of Medicine, University of California, Los Angeles.
authors.forename: Akishige
authors.initials: A
authors.lastname: Hokugo
authors.forename: Sarah
authors.initials: S
authors.lastname: Sorice
authors.forename: Anisa
authors.initials: A
authors.lastname: Yalom
authors.forename: James C
authors.initials: JC
authors.lastname: Lee
authors.forename: Andrew
authors.initials: A
authors.lastname: Li
authors.forename: Patricia
authors.initials: P
authors.lastname: Zuk
authors.forename: Reza
authors.initials: R
authors.lastname: Jarrahy
mesh_terms: D000469:Alkaline Phosphatase / Q000096:biosynthesis / Q000235:genetics; D000818:Animals; D055396:Bone Morphogenetic Protein 2 / Q000008:administration & dosage*; D002454:Cell Differentiation / Q000187:drug effects; D002478:Cells, Cultured; D003124:Colorimetry; D004305:Dose-Response Relationship, Drug; D005786:Gene Expression Regulation / Q000187:drug effects; D053823:Hedgehog Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D008297:Male; D059630:Mesenchymal Stem Cells / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D015675:Osteocalcin / Q000096:biosynthesis / Q000235:genetics; D010012:Osteogenesis / Q000187:drug effects*; D012313:RNA / Q000235:genetics; D011817:Rabbits; D060888:Real-Time Polymerase Chain Reaction; D011987:Receptors, Steroid / Q000008:administration & dosage*; D015398:Signal Transduction / Q000187:drug effects; D014704:Veratrum Alkaloids / Q000494:pharmacology; D000098825:Oxysterol Binding Proteins
chemical_list: D055396:Bone Morphogenetic Protein 2; D053823:Hedgehog Proteins; D011987:Receptors, Steroid; D014704:Veratrum Alkaloids; D000098825:Oxysterol Binding Proteins; D015675:Osteocalcin; D012313:RNA; D000469:Alkaline Phosphatase; C000541:cyclopamine